JP3029313B2 - Glass fiber reinforced polyolefin resin molded article and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automotive parts and home electric parts.
Glass fiber reinforced po
The present invention relates to a polyolefin resin molded product and a method for producing the same .

[0002]

2. Description of the Related Art Glass fiber reinforced polypropylene has high mechanical strength and is used as an important material in the field of industrial materials. However, this glass fiber reinforced polypropylene has the disadvantage that the warpage is large and the impact strength is low,
Its use is limited. For this reason, some proposals have conventionally been made to solve the disadvantages of glass fiber reinforced polypropylene.

For example, Japanese Patent Publication No. 62-34258 and Japanese Patent Publication No. 61-533
No. 84 proposes a method of suppressing warpage by adjusting the MI (melt index) of polypropylene. However, this method has an insufficient effect of suppressing the warpage and cannot improve the impact strength. Further, Japanese Patent Publication No. 53-121843 and Japanese Patent Publication No. 59-226041 propose a method in which glass fiber and a plate-like filler such as mica are used in combination.However, this method is somewhat effective in preventing warpage deformation. Although effective, the impact strength is reduced. In addition, in Japanese Patent Publication No. 59-2294,
Although a method of adding an amorphous elastic body (elastomer) has been proposed, this method is effective in suppressing warpage deformation and improving impact strength, but has an excellent tensile strength characteristic of glass fiber reinforced resin. However, there is a problem that bending strength, heat resistance (HDT) and the like are significantly impaired. The present invention has been made in view of the above circumstances, and has excellent tensile strength, bending strength, and heat resistance (H
DT), a glass fiber reinforced polyolefin resin molded article having a small warpage and high impact strength.
Another object of the present invention is to provide a manufacturing method by which such molded articles can be efficiently obtained .

[0004]

Means and Action for Solving the Problems The present inventors have
As a result of intensive studies to achieve the above object, a specific low-density polyethylene and a modified polyolefin were added to the polypropylene resin, and by maintaining the average fiber length of the glass fibers in the molded product at a constant length. It has been found that the above object is effectively achieved. That is, the present inventors have found that when low-density polyethylene is added to a polypropylene-based resin, the warpage is reduced, but the tensile strength, bending strength, heat resistance (H
DT) is remarkably reduced and cannot be used, and the impact strength is hardly improved. On the other hand, a specific low-density polyethylene and a modified polyolefin are added, and the fiber length of the glass fiber in the molded product is 1 to 1. It has been found that by keeping the thickness at 6 mm, the tensile strength, the bending strength, and the heat resistance (HDT) can be kept high, and the impact strength can be greatly improved. Reached.

Accordingly, the present invention relates to (a) a polypropylene resin having a melt index of 5 g / 10 min or more, from 45 to 85% by weight of the total amount of the components (a), (b) and (c); ) Low-density polyethylene having a density of 0.89 to 0.93 g / cm3, a melt index of 5 g / 10 min or more, and an MI ratio of 0.5 to 5 represented by the following formula: (a), (b), (C) 5 to 25% by weight of the total amount of the components
MI ratio = MI (a) / MI (b) MI (a): Melt index of component (a) MI (b): Melt index of component (b) (c) Average fiber diameter is 3 to 20 μm, A glass fiber having an average fiber length of 2 to 6 mm in a molded product is shown in (a),
10 to 40% by weight of the total amount of the components (b) and (c); and (d) the total amount of the components (a), (b) and (c) is 100.
A modified polyolefin is used in an amount of 0.1 to 10 parts by weight with respect to parts by weight. The glass fiber reinforced polyolefin resin molded product is characterized in that the HDT obtained is 150 ° C. or higher and the IZOD impact strength measured according to JIS K7110 is 20.2 kgcm / cm or higher. Also, another aspect of the present invention,
A method for producing a glass fiber-reinforced polyolefin resin molded article, comprising the following steps (I) to (III). (I) A fiber bundle made of glass fiber having an average fiber diameter of 3 to 20 μm is continuously passed through the melted polypropylene resin (a) and (b), and the fiber bundle is impregnated with the melt. (II) cutting the formed strand, and forming a reinforced resin (master batch) in which the glass fiber and the polypropylene resin are compounded without melt-kneading. (III) a step of melt-kneading the reinforced resin (master batch).

Hereinafter, the present invention will be described in more detail.
First, each component will be described. (A) Component As the component (a), a polypropylene resin having an MI of 5 g / 10 min or more, preferably 10 to 60 g / 10 min or more is used. If the MI is less than 5 g / 10 minutes, the moldability of the composition is deteriorated, and the warpage is increased. (A)
As the polypropylene resin as the component, a polypropylene homopolymer, an ethylene-propylene copolymer, or the like can be used. More specifically, an isotactic propylene homopolymer having crystallinity, a copolymerized portion composed of an ethylene propylene random copolymer having a low ethylene unit content, or a homopolymerized portion composed of a propylene homopolymer and an ethylene unit. A block copolymer of substantially crystalline propylene and ethylene, which is commercially available as a so-called propylene block copolymer, comprising a copolymer part composed of a relatively high content of ethylene propylene random copolymer, Alternatively, each of the homopolymerized portions or copolymerized portions in the block copolymer is substantially crystalline propylene-ethylene-α, which is obtained by further copolymerizing an α-olefin such as butene-1,2-methylpentene-1. -Olefin copolymers and the like are preferred. Among these, a crystalline ethylene-propylene copolymer having an ethylene content of 3 to 10% by weight is particularly preferable. The blending amount of the component (a) is 45 to 8 of the total amount of the components (a), (b) and (c).
It is 5% by weight, preferably 50-80% by weight.

Component (b) The component (b) has a density of 0.89 to 0.93 g / c.
m3, preferably 0.90 to 0.92 g / cm3, and a melt index of 5 g / 10 min or more, preferably 10 to 1
00g / 10 min, and the MI ratio represented by the above formula is 0.1.
Low density polyethylene (LDPE) of 5-5, preferably 1-4 is used. 0.89g / cm3 density
If it is less than 10%, the tensile strength, bending strength and HDT may decrease. If it exceeds 0.93 g / cm3, the effect of suppressing the warpage is small. When the MI is less than 5 g / 10 minutes, the effect of suppressing the warpage is small. When the MI ratio is out of the range of 0.5 to 5, the effect of suppressing the warpage is small. The component (b) includes linear low-density polyethylene (L-LDPE), low-density polyethylene (LDPE), and ultra-low-density linear polyethylene (V-
LDPE) and the like.
Preferred is a linear low density polyethylene (L-LDPE) of 90 to 0.92 g / cm3. The compounding amount of the component (b) is 5 to 25% by weight, preferably 10 to 20% by weight of the total amount of the components (a), (b) and (c). If it is less than 5% by weight, the effect of suppressing the warpage is small, and if it exceeds 25% by weight, the strength, rigidity and heat resistance are reduced.

Component (c) The component (c) has a fiber diameter of 3 to 20 μm, preferably 6 to 15 μm, and a fiber length of 1 to 6 m in a molded article.
m, preferably 2-5 mm glass fiber. If the fiber diameter is less than 3 μm, the fiber is easily broken, and it is difficult to keep the fiber length in the molded product at 1 to 6 mm. is there. Fiber length in molded product is 1m
If it is less than m, the warpage is increased, the impact strength is reduced, and the strength, rigidity and heat resistance are insufficient. 6m
If it exceeds m, moldability will be reduced, and poor biting and classification during injection molding may occur. The amount of component (c) is 10% of the total amount of components (a), (b) and (c).
-40% by weight, preferably 15-30% by weight. 1
If the content is less than 0% by weight, the strength, rigidity and heat resistance may be insufficient, and the warpage may increase. When the content exceeds 40% by weight, the moldability is reduced and the appearance of the molded product is deteriorated.

Component (d) The modified polyolefin of the component (d) is not particularly limited, but an acid-modified polyolefin can be suitably used. This acid-modified polyolefin is obtained by mixing a polyolefin with an α, β-unsaturated carboxylic acid and / or an acid anhydride thereof in a solvent or in a melt-kneaded state.
The polyolefin is modified with an α, β-unsaturated carboxylic acid and / or an acid anhydride thereof by reacting with a radical generator. Examples of the polyolefin include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, polybutylene, polybutadiene, cis-polybutadiene rubber,
Ethylene-propylene polymer, further ethylene-propylene-cyclopentadiene copolymer, ethylene-
Olefin homopolymers or copolymers such as ethylene-propylene-diene copolymers such as propylene-1,4-cyclooctadiene copolymer are exemplified.

On the other hand, as the α, β-unsaturated carboxylic acid and its acid anhydride, those having 20 or less carbon atoms, particularly those having 4 to 16 carbon atoms, are suitable, for example, acrylic acid, methacrylic acid,
Ethacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, 3,6-endomethylene-2,3,4,6
-Tetrahydrocis-phthalic acid and acid anhydrides thereof. Of these, acid anhydrides are more preferable than carboxylic acids, and maleic anhydride is particularly preferable. This maleic anhydride is generally used in a proportion of 0.1 to 50 parts by weight based on 100 parts by weight of the polyolefin.

The radical generator is not particularly limited as long as it promotes the reaction between the polyolefin and the α, β-unsaturated carboxylic acid or its anhydride.
For example, benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, dicumyl peroxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, 2,5-dimethyl-2,5-di (t-
(Butylperoxy) hexane, di-t-butyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide and the like. These radical generators are appropriately selected according to the type of reaction, the type of the polyolefin and the modifier used, and the like.

In the present invention, as the modified polyolefin, polypropylene, polyethylene or ethylene-propylene copolymer modified with maleic acid, acrylic acid or anhydride thereof, particularly maleic acid-modified polypropylene, is particularly preferred. The amount of the component (d) is (a),
0.1 parts by weight based on 100 parts by weight of the total amount of the components (b) and (c).
It is 1 to 10 parts by weight, preferably 0.5 to 5 parts by weight.
If the amount is less than 0.1 part by weight, the effect of modifying the interface is small, and the strength and heat resistance are reduced. If the amount exceeds 10 parts by weight, no further improvement in strength and heat resistance can be expected, resulting in a cost map, which is not economical and, on the contrary, the impact strength may decrease. Further, additives such as an antioxidant, a weathering agent, a release agent, a dispersant, and a pigment can be appropriately added to the composition of the present invention as needed.

Although the method for producing the composition of the present invention is not limited, the following method can be particularly preferably employed (Japanese Patent Application No. 1-322694). That is, the fiber bundle (glass fiber) is contained in the molten thermoplastic resin (component (a), component (b)).
Is a method of manufacturing a fiber-reinforced resin molding material by continuously passing through, impregnating the fiber bundle with the molten resin, drawing out from the die, and curing the resin, and impregnating the fiber bundle with the molten resin. In this case, the fiber bundle is wound around the rod in a state where at least one side is inclined by a predetermined angle with respect to a straight line passing through the center of the rod. In this case, preferably, the fiber bundle is wound around the rod with at least one side having an inclination angle of 10 degrees or more with respect to a straight line passing through the center of the rod. Also,
The fiber bundle is brought into contact with a plurality of rods so that the fiber bundle forms a waveform as needed. Therefore, a fiber bundle composed of glass fibers having an average fiber diameter of 3 to 20 μm is continuously passed through (I) the molten polypropylene resins (a) and (b).
Impregnating the melt to form a continuous strand of glass fibers; and (II) cutting the formed strand and reinforcing the glass fiber and polypropylene resin into a composite without melt-kneading. A glass fiber reinforced polyolefin resin molded article can be produced by including a step of producing a resin (masterbatch) and a step of (III) melt-kneading the reinforced resin (masterbatch).

By employing the method of Japanese Patent Application No. 1-322694, it is possible to produce a reinforced resin in which glass fiber and polyolefin are compounded without using a kneading step. The length can be kept long, so that a composition having excellent strength, rigidity and heat resistance can be obtained. That is, the conventional glass fiber reinforced polyolefin is usually produced by kneading a polyolefin and glass fiber with an extruder, so that the glass fiber breaks and the average fiber length of the glass fiber in the molded product is 0.2.
０．５0.5 mm, which has the disadvantage of low impact strength and large warpage deformation. In contrast,
In order to improve the above drawbacks, it has been proposed to blend an elastomer with a polyolefin.However, this method has been found to improve the impact strength and warpage, but the strength and heat resistance are improved because the elastomer is blended. There has been a problem that properties and rigidity are significantly reduced. However, by adopting the above method, such a problem is surely solved.

[0015]

Next, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. [Manufacture of master batch] According to the method described in Japanese Patent Application No. 1-322694, an MI of 30 was obtained.
g / 10min polypropylene 40% by weight and fiber diameter 13μ
After manufacturing a strand in which the glass fiber consisting of 60% by weight of the glass fiber of m was continuous, cutting was performed so that the pellet length became 6 mm, and this was used as a master batch. This master batch was designated as MB-1. Example 1 MI = 30 g / 10 min crystalline ethylene-propylene copolymer, density 0.92 g / cm ³ , MI = 20 g / 10
A test piece was prepared by injection molding using the linear low-density polyethylene, MB-1 and maleic acid-modified polypropylene. Tables 1 and 2 show the compositions and physical properties of the obtained test pieces.
Shown in

Comparative Example 1 A crystalline ethylene-propylene copolymer having an MI of 30 g / 10 min, a density of 0.92 g / cm ³ , and an MI of 20 g / 10
Minute low density polyethylene, fiber diameter 13μm, length 3
After a predetermined amount of glass fiber and maleic acid-modified polypropylene were blended in a predetermined amount, the mixture was kneaded with a biaxial kneader (side feed of glass fiber only) to obtain a test piece (pellet).
Tables 1 and 2 show the compositions and physical properties of the obtained test pieces. [Comparative Example 2] A test piece was prepared in the same manner as in Comparative Example 1, except that the linear low-density polyethylene was replaced with an amorphous ethylene-propylene copolymer (EPR) having a Mooney viscosity of 24. Created. Table 1 shows the composition and physical properties of the obtained test piece.
It is shown in Table 2. [Example 2] A test piece was prepared in the same manner as in Example 1, except that linear low-density polyethylene having a density of 0.905 g / cm ³ and MI = 10 g / 10 minutes was used. . Tables 1 and 2 show the compositions and physical properties of the obtained test pieces.

[Manufacture of Masterbatch] A masterbatch was prepared in the same manner as in the above-mentioned method of manufacturing MB-1, except that polypropylene having MI of 10 g / 10 min was used. This was a master batch MB-2. Example 3 MI = 10 g / 10 min crystalline ethylene-propylene copolymer, density 0.92 g / cm ³ , MI = 8 g / 10 min linear low density polyethylene, modified with MB-2 and maleic acid Test pieces were prepared by injection molding using polypropylene. Tables 1 and 2 show the compositions and physical properties of the obtained test pieces. [Comparative Example 3] A test piece was prepared in the same manner as in Example 3 except that the linear low-density polyethylene was replaced with a high-density polyethylene having a density of 0.96 g / cm ³ and an MI of 1 g / 10 minutes. It was created. Tables 1 and 2 show the compositions and physical properties of the obtained test pieces.

The physical properties in Table 2 were measured by the following methods. Flexural properties: Measured according to JIS K7203. Bending characteristics at 120 ° C .: Measured according to JIS K7203. HDT (high load): Measured according to JIS K7207. IZOD impact strength: measured according to JIS K7110. Amount of warpage: As shown in FIG. 1, a disk having a diameter D of 20 mm and a thickness t of 1.5 mm is formed by injection molding, and the height from the lowest point on the bottom surface of the disk to both sides of the upper end. A,
b was measured and obtained by the following equation. Warpage deformation (%) = (a + b−2t) / 2DX100

[0019]

[Table 1]

[0020]

[Table 2]

From the results in Table 2, the following facts can be understood. The glass fiber reinforced resin molded article of the present invention is superior in strength and heat resistance to the conventional one (Examples 1 to 5).
3 and Comparative Example 2). Even if the composition of the molded article is the same, the physical properties and the warpage are greatly improved due to the different fiber lengths of the glass fibers (Example 1 and Comparative Example 1).
And comparison). That is, in the conventional fiber length, even if polyethylene is added to improve the warpage deformation, the physical properties are too large and the use is not endurable, but by controlling the fiber length, excellent performance is exhibited. You can see that. When the polyethylene is outside the scope of the present invention, the physical properties are reduced, and the effect of improving the warpage is small (comparison between Examples 1 to 3 and Comparative Example 3).

[0022]

As described above, the glass fiber of the present invention is
Obtained from the fiber-reinforced resin molded article and the production method of the present invention
Glass fiber reinforced resin molded article, glass fiber reinforced resin molding
While maintaining excellent tensile strength, bending strength, and heat resistance, which are inherent characteristics of the product , warpage is suppressed and high impact strength is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a method of measuring a warpage deformation amount.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI C08L 51:06 23:26) (58) Investigated field (Int.Cl. ⁷ , DB name) C08L 23/10 C08K 7/14

Claims (2)

(57) [Claims] (A) a melt index of 5 g / 10
(A), (b),
(C) 45 to 85% by weight of the total amount of the components; (b) a density of 0.89 to 0.93 g / cm ³ ;
The index is 5 g / 10 min or more and is represented by the following formula:
Low density polyethylene having an MI ratio of 0.5 to 5
5 to 25% by weight of the total amount of the components (a), (b) and (c)
If, MI ratio = MI (a) / MI ( b) MI (a): component melt index MI of (a) (b): melt index (c) an average fiber diameter of the component (b) is at 3 to 20 [mu] m, In molded articles
Glass fibers having an average fiber length of 2 to 6 mm
10 to 40% by weight of the total amount of the components (b) and (c); and (d) the total amount of the components (a), (b) and (c) is 100.
0.1 to 10 parts by weight of modified polyolefin based on parts by weight
It consists of a down and, 120 ° C. flexural strength measured according to JIS K7203
And 321Kg / cm ² or more values of, 150 HDT measured according to JIS K7207
℃ the above value, IZOD impact strength was measured according to JIS K7110
Characterized by a value of 20.2 kgcm / cm or more
Glass fiber reinforced polyolefin resin molded products. 2. The method for producing a glass fiber-reinforced polyolefin resin molded product according to claim 1, comprising the following steps (I) to (III). (I) A fiber bundle made of glass fiber having an average fiber diameter of 3 to 20 μm is continuously passed through the melted polypropylene resin (a) and (b), and the fiber bundle is impregnated with the melt. (II) cutting the formed strand, and forming a reinforced resin (master batch) in which the glass fiber and the polypropylene resin are compounded without melt-kneading. (III) a step of melt-kneading the reinforced resin (master batch).